WO2013191610A2

WO2013191610A2 - Method for attaching to a wireless communications network

Info

Publication number: WO2013191610A2
Application number: PCT/SE2012/051482
Authority: WO
Inventors: Peter Hedman; Magnus Karlsson
Original assignee: Telefonaktiebolaget L M Ericsson (Publ)
Priority date: 2012-06-21
Filing date: 2012-12-21
Publication date: 2013-12-27
Also published as: WO2013191610A3

Abstract

A method for attaching a wireless communications device (101) to a wireless communications network, the wireless communications network providing data communication, the method comprising communicating, between the wireless communications device and the wireless communications network, an indication (524, 630) that a selected one of the wireless communications device and the wireless communications network supports attachment of the wireless communications device to the wireless communications network without establishing an association to a packet data network (107).

Description

Method for attaching to a wireless communications network Technical Field

Disclosed herein are embodiments of methods and corresponding devices for attaching a wireless communications device to a wireless communications network, such as a wireless communications network for packet based data communication, in particular an internet protocol network.

Background

The Universal Mobile Telecommunication System (U M T S ) i s a third generation mobile cellular system for networks based on the Global System for Mobile Communication (GSM) standard. The evolved UMTS Terrestrial Radio Access (E-UTRA) denotes the air interface of the so-called Long Term Evolution ( LTE ) upgrade path for m obi le networks. The E-UTRAN of the Long Term Evolution (LTE) thus denotes a standard for wireless communication of high-speed data communication for mobile phones or other User Equipment (UE), data terminals, devices for Machine Type Communication (MTC), and similar wireless communications devices. The E- UTRAN system is also referred to as the Evolved Packet System (EPS). E- UTRAN is based on the known Global System for Mobile Communication (GSM)/Enhanced Data for GSM Evolution (EDGE) and Universal Mobile Telecommunication System (UMTS)/High Speed Packet Access (HSPA) network technologies, though providing an increased capacity and speed using new modulation techniques. The E-UTRAN standard is developed by the 3GPP (3rd Generation Partnership Project). The EPS comprises a core network (called Evolved Packet Core - EPC) and a Radio Access Network (RAN).

The EPS has been developed to provide an always-on IP connectivity, which implies that during EPS attachment to the EPC, the wireless communications device is also required to make a request for a Packet Data Network (PDN) connection. A P D N connection is an association between a wireless communications device and a PDN, e.g. an Internet Protocol (IP) network. The association may be represented by an IP address, such as an IPv4 address and/or a /64 IPv6 prefix. A PDN is identified by an Access Point Name (APN) and a PDN is accessed via a PDN gateway (P-GW). A PDN is responsible for the I P address/prefix management. On a wireless communications device, a PDN Connection may be visible to an IP stack as a virtual network interface. The Mobility Management Entity (MME) is a control node of the LTE access- network. It is respons i b le for the tracking of idle-mode wireless communications devices and paging procedures including retransmissions. It is also involved in the bearer activation/deactivation process and is also responsible for choosing a Serving Gateway (SGW) for a wireless communications device at the initial attach process of the wireless communications device and at the time of intra-LTE handover involving Core Network (CN) node relocation. The SGW is a node of the LTE network that routes and forwards user data packets. The MME is further responsible for interacting with a Home Subscriber Server (HSS) for performing user authenticating. The HSS is a central database that has stored thereon user- related and subscription-related information.

One of the important procedures in which the EPS Mobility Management (EMM) is involved is the so-called attach procedure, also referred to as EMM attach. The wireless communications device invokes the attach procedure to attach to the LTE network, e.g. when the wireless communications device is powered ON or enters an LTE coverage area. During the EPS attach procedure the wireless communications network activates a default EPS bearer context. A PDN connection would previously have been a necessity for Mobile Terminating (MT) services using IP. However, EPS has been modified to also allow non-IP connectivity via a control plane such as Short Message Service (SMS), i.e. in principle MT service can be initiated without using the always- on PDN connection.

The 3GPP Technical Specification (TS) 23.401 "General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access" (Release 1 1 , version 1 1 .1 .0) describes in section 4.6 the EPS Mobility Management and Connection Management states.

To more efficiently provide support for an anticipated growth in wireless communications devices used for Machine Type Communication (MTC), the standard 3GPP Technical Specification 22.368 (Release 10, version 10.4.0) includes a generic requirement in section 7.1 .1 that "the system shall provide mechanisms to efficiently maintain connectivity for a large number of MTC Devices". Keeping always at least one E PS bearer for wireless communications devices which seldom communicate, always originate services from the wireless communications device, or use MT-SMS for initiating communication (e.g. using Device Triggering) may thus be regarded as a wasteful use of resources (e.g. an increase in signaling during mobility scenarios).

Summary

Based on the above, described herein is a method for attaching a wireless communications device to a wireless communications network providing data communication, in particular high-speed data communication such as packet- based data com m un ication . E m bodi m ents of the m ethod com prise communicating, between the wireless communications device and the wireless communications network, an indication that a selected one of the wireless communications device and the wireless communications network supports attachment of the wireless communications device to the wireless communications network without establishing an association to a packet data network.

Embodiments of the method disclosed herein thus facilitate avoiding wasteful use of communications resources by facilitating a reduction of the signalling between wireless communications devices and the wireless communications network infrastructure.

In some embodiments communicating comprises sending a connectivity request by the wireless communications device to a control node of the wireless communications network, the connectivity request comprising an indication that the wireless communications device supports attachment to the wireless communications network without establishing an association to a packet data network.

In an alternative embodiment, the indication is an indication that the wireless communications network supports attachment of a wireless communications device without establishing an association to a packet data network; and communicating the indication comprises receiving a broadcast message by the wireless communications device from the wireless communications network indicative of whether the wireless communications network supports attachment of a wireless communications device without establishing an association to a packet data network; and the method further comprises sending a connectivity request responsive to the received broadcast message. In some embodiments, the wireless communications network is an EPS communications network or another suitable communication network. In one embodiment, the wireless communications network is an EPS network as specified in TS 23.401 , version 1 1 .1 .0: "General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access (Release 1 1 )".

For the purpose of the present descri ption , attach i ng a wi re less communications device to a wireless communications network is intended to refer to any suitable registration procedure for registering a wireless communications device with a wireless communications network so as to allow the wireless communications device to receive services via the wireless communications network that require registration, such as voice and/or data communications. Embodiments of such a registration procedure may thus comprise communicating a device identifier of the wireless communications device to the wireless communications network so as to allow the network to verify whether the wireless communications device is authorized to receive such services. Em bodiments of the registration procedure may further comprise establishment of an association between the wireless communications device and a packet data network. Such an association may be represented by an identification of respective end points of the association and an identification of the type of service that makes use of the association. The end points may be the wireless communications device and a gateway to a packet data network; exam ples of types of services may include conversational voice, streaming video, signalling, best effort data, etc. The association may be a virtual connection of the endpoints in a connection- oriented transmission network. For example, in the context of LTE, such an association is established as a so-called EPS default bearer, i.e. the EPS bearer which is first established for a new PDN connection and remains established throughout the lifetime of the PDN connection. In the context of LTE, the registration procedure is also referred to as attach procedure or EMM attach. In the context of LTE, embodiments of the method disclosed herein thus allow the wireless communications network to avoid setting up a PD N connection requested by the wireless communications device at the same time as an EMM attach. This may be done by the wireless communications device including an indication that the wireless communications device supports the capability to be EMM attached without any PDN connection, i.e. without a default EPS bearer, which enables the wireless communications network to reject or deactivate such PDN connection without detaching the wireless communications device.

In some embodiments, the connectivity request comprises an indication by the wireless communications device whether the wireless communications device has an im mediate need for communicating via the data packet network. Consequently, the wireless communications device is given the additional opportunity to indicate whether the wireless communications device has the intention to "immediately" make use of the PDN connection that is to be created responsive to the issued PDN connectivity request sent at the same time as the EMM attach. The wireless communications device may thus determine the need for having a PDN connection established upon attach (e.g. because the wireless communications device has data to be sent), or whether a PDN connection may be established at a later point in time. Such indication enables the wireless communications device to retain the possibility of efficiently attaching and setting up a PDN connection at the time of the EMM attach and of immediately making use of the PDN connection, e.g. for perform ing some application layer registration. Alternatively, the wireless communications network may decide to perform an EMM attach while rejecting the PDN connectivity request for the purpose of keeping the resource usage by the wireless communications device at a low level, though such rejection may lead to increased signalling as the reject would have been followed by a subsequent separate PDN connectivity request issued by the wireless communications device. The term "immediate need" as used herein refers to a determination made by the wi re l ess com m u n i cati ons dev ice as to whether the w i re l ess communications device intends to make use of an established PDN connection immediately after or at least relatively soon after completion of the network attachment. Within which time frame the wireless communications device regards making use of the PDN connection as "immediate" may vary between wireless communication devices and/or may depend on the specific situation. Nevertheless, the mechanism described herein allows a wireless communications device to influence whether PDN connection is established upon network attachment or not.

E m bod i m e nts of the m ethod d i scl osed herein allow a wireless communications device to make an EMM attach (or EMM and International Mobile Subscriber Identity (IMSI) attach registering for both EPS and non- EPS services) without requiring the wireless communications network to accept the issued ESM PDN connectivity request, which will save resources and ease implementation compared to e.g. deactivating a PDN connection once it has been established.

Embodiments of the method disclosed herein may be implemented by a wireless communications device, e.g. a mobile unit, specifically manufactured for this purpose, or by a suitably program med conventional wireless communications devices for mobile communications, which may be used for regular communications purposes.

S im ilarly, according to one aspect, a control node of the wireless communications network may be adapted to perform corresponding method steps facilitating efficient attachment of a wireless communications device, such as a UE. To this end, disclosed herein is a method for attaching a wireless communications device to a wireless communications network, the wireless communications network comprising at least one control node, the method comprising:

- com m un icating an ind ication that a selected one of the wireless communications device and the wireless communications network supports attachment of the wireless communications device to the wireless communications network without establishing an association to a packet data network;

- determining, by the control node, whether to provide an attachment of the wireless communications device to the wireless communications network with or without establishing an association to a packet data network;

- sending a message from the control node to the wireless communications device indicative of whether the wireless communications device is attached to the wireless communications network with or without establishing an association to a packet data network.

Communicating may comprise receiving, by the control node, a connectivity request from a wireless communications device, wherein the connectivity request comprises an indication that the wireless communications device supports attachment to the wireless com m unications network without establishing an association to a packet data network. Alternatively, communicating comprises causing the wireless communications network to se n d a b road cast m ess ag e i n d i cat i ve of wh eth e r th e w i re l ess communications network supports attachment of a wireless communications device without establishing an association to a packet data network.

The data packet network may be an IP network, and the association to the data packet network may comprise an IP address. In other embodiments, the data packet network may be a cellular operator's portal. In yet another embodiment the data packet network may be another type of packet- switched data network. The indications by the wireless communications device may be included in or appended to a connectivity request, e.g. using known message structures. For example, one or both indications may be included as suitable fields or flags in a suitable message format.

The communication between the wireless communications device and the control node may be a direct communication or it may be performed via one or more other nodes, e.g. other nodes of the wireless communications network.

The features of embodiments of the methods described herein may be implemented in software and carried out on a mobile device, a control node of the wireless communications network, or other data processing system ca used by the executi on of com puter-executable instructions. The instructions may be program code means loaded in a memory, such as a Random Access Memory (RAM), from a storage medium or from another computer via a computer network. Alternatively, the described features may be implemented by hardwired circuitry instead of software or in combination with software.

Disclosed herein are different aspects including the method described above and in the following, corresponding methods, apparatus, devices, and/or product means, each yielding one or more of the benefits and advantages described in connection with the first mentioned aspect, and each having one or more embodiments corresponding to the em bodiments described in connection with the first mentioned aspect and/or disclosed in the appended claims.

According to one aspect, disclosed herein is a wireless communications device for a wireless communications system, the wireless communications device comprising a processing unit and a radio communications circuit; wherein the wi re less com m u n i cati ons d evice is confi g u red for communication, between the wireless communications device and the wireless communications network, of an indication that a selected one of the wireless communications device and the wireless communications network supports attachment to the wireless communications network without establishing an association to a packet data network.

In some embodiments, the processing unit is configured to cause the radio communications circuit to send a connectivity request to a control node of the wireless com m unications network, wherein the connectivity request comprises an indication that the wireless communications device supports attachment to the wireless communications network without establishing an association to a packet data network. The radio communications circuit may be any circuitry or device configured to provide radio-frequency communication with a wireless communications network, e.g. an LTE communications network, an EPS communications network, or another suitable communication network. In some embodiments, the wireless communications network is an EPS network, e.g. as specified in TS 23.401 , version 1 1 .1 . 0 : "General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E- UTRAN) access (Release 1 1 )".

The processing unit may be any circuitry or device configured to perform data processing, e. g . a suitably program med m icroprocessor, a Central Processing Unit (CPU) of a computer, of a handheld terminal, or of another processing device, a dedicated hardware circuit, etc., or a combination of the above. The wireless communications device may comprise a memory or other suitable storage medium having computer program code stored thereon adapted to cause, when executed by the processing unit, the wireless communications device to perform the steps of embodiments of the method described herein.

Examples of a wireless communications device include User Equipment (UE) such as a mobile phone, smart phone, or another suitable communications device.

In some embodiments, the wireless communications device is further adapted to insert an indication into the connectivity request as to whether the wireless communications device has an immediate need for communicating via the data packet network. Hence, a wireless communications device may thus be configured to indicate, at the same time as the attach procedure, whether it has the intention of "immediately" making use of a PDN connection to be created due to an issued PDN connectivity request.

In some embodiments, the radio communications circuit is adapted to receive a broadcast message from the wireless communications network indicative of whether the wireless communications network supports attachment of a wireless communications device without establishing an association to a packet data network; and wherein the wireless communications device is further adapted to cause the radio communications circuit to send a connectivity request for requesting, responsive to the received broadcast message, attachment to the wireless communications network either with or without establishing an association to a packet data network. Hence, some embodiments of the wireless communications device may be configured to test received broadcast information and, based on the received information, to either use a conventional EMM Attach that always includes a PDN connection request (if standalone EMM Attach is not supported), or to determine whether to use a standalone EMM Attach, if standalone EMM Attach is supported by the wireless communications network. According to yet another aspect, disclosed herein is a control node of a wireless communications network comprising:

- an interface circuit adapted to receive a connectivity request from a wireless communications device;

- a processing unit adapted to determine whether to provide an

attachment of the wireless communications device to the wireless communications network with or without establishing an association to a packet data network; and

- wherein the interface circuit is further adapted to send a message to the wireless communications device indicative of whether the wireless communications device is attached to the wireless communications network with or without establishing an association to a packet data network.

The interface circuit may be any circuitry or device configured to provide data communication between the control node and the wireless communications network, where the data communication may be performed directly or via other nodes of the communications network. The processing unit may be any circuitry or device configured to perform data processing, e.g. a suitably programmed microprocessor, a CPU of a computer, a dedicated hardware circuit, etc., or a combination of the above. In particular, the control node may comprise a memory or other suitable storage medium having computer program code stored thereon adapted to cause, when executed by the processing unit, the control node to perform the steps of embodiments of the method described herein.

The control node may be implemented by a suitably programmed computer, by a dedicated network component, or the like. In some embodiments, the control node may be a single device while, in other embodiments, the control node may be implemented by a plurality of devices e.g. by a plurality of computers interconnected via a suitable computer network, by a virtual machine, and/or the like. Hence, in some embodiments, the steps of embodiments of the method described herein may be performed by a wireless communications system in a distributed manner. In some embodiments, the control node is or comprises a Mobility Management Entity (MME) of an LTE access-network.

In some embodiments, the connectivity request comprises an indication that the wireless communications device supports attachment to the wireless communications network without establishing an association to a packet data network. In some embodiments, the received connectivity request comprises an indication by the wireless communications device whether the wireless communications device has an immediate need for communicating via the data packet network; and the processing unit of the control node is further adapted to cause the control node to provide an attachment of the wireless communications device to the wireless communications network with or without establishing an association to a packet data network responsive to the received indication. In some embodiments, the control node and/or another entity of the wireless communications network is configured to decide whether to reject a PDN connectivity request for the purpose of keeping the resource usage by the wireless communications device at a low level. If the control node and/or other entity of the wireless communications network decides to reject the PDN connectivity request, the control node and/or other entity of the wireless configuration network may be configured to send an EMM Attach Accept message containing a PDN Connectivity Reject indication indicating an ESM cause code, where the ESM cause code indicates that the PDN connection was not established, but that the wireless communications device can request it again as a standalone procedure at a later point in time when there is a need for it.

If the control node and/or other entity of the wireless communications network decides to reject the PDN connectivity request, the control node and/or other entity of the wireless configuration network may be configured to send an EMM Attach Accept message containing an ESM Activate Default EPS Bearer Context Request but with an indication to the wireless

communications device that the connection will only be a placeholder/dummy (in order to keep the existing principles of dependencies between EMM and ESM) and that the connection cannot be used for obtaining receiving communications or other services.

In some embodiments, the control node and/or another entity of the wireless communications network is configured to broadcast (e.g. by causing a Radio Access Network (RAN) of the wireless communications network to broadcast) information that indicates the wireless communications network's support of the standalone EMM Attach functionality. Accordingly, in some embodiments the control node is further adapted to cause the wireless communications network to send a broadcast message indicative of whether the wireless communications network supports attachment of a wireless communications device without establishing an association to a packet data network. Brief description of the drawings

The above and/or add itional objects, features and advantages of embodiments of the methods, systems and devices disclosed herein, will be further elucidated by the following illustrative and non-limiting detailed description of embodiments of the methods, systems and devices disclosed herein, with reference to the appended drawings, wherein: Figure 1 schematically illustrates parts of an embodiment of a wireless communications system.

Figure 2 shows a schematic block diagram illustrating relevant MME hardware.

Figure 3 shows a schematic block diagram of an exam ple of a wireless communications device.

Figure 4 schematically illustrates an embodiment of the signalling between the wireless communications device and the M M E during the attach procedure for attaching a wireless communications device to the LTE network.

Figure 5 shows a flow diagram of the steps performed by the wireless communications device.

Figure 6 illustrates an embodiment of a connectivity request message.

Figure 7 illustrates an embodiment of a response message form the control node to the wireless communications device.

Detailed description

In the following description, reference is made to the accompanying figures, which show by way of illustration how embodiments of the methods, systems and devices disclosed herein may be practiced.

Figure 1 schematically illustrates parts of an embodiment of a wireless communications system , in particular parts of an LTE comm unications system. The system wireless communications device 1 01 , e. g. a mobile phone, smart phone, or other suitable User Equipment (UE). The system further comprises a base station 102, also called evolved NodeB (eNB), with which the wireless communications device is adapted to communicate via a wireless radio-frequency connection. The system further comprises a Mobility Management Entity (MME) 103. Th e M M E i s a control node of the communications system and it may be responsible for the tracking of idle- mode wireless communications device and paging procedures including retransmissions. Th e M M E m ay fu rthe r be involved in the bearer activation/deactivation process and is also responsible for choosing a Serving Gateway (SGW) for a wireless communications device at the initial attach process of the wireless communications device and at time of intra- LTE handover involving Core Network (CN) node relocation.

The SGW 105 is a node of the LTE network that routes and forwards user data packets, in particular to and from a Packet Data Network (PDN) 107 via a Packet data network Gateway (P-GW) 106.

The MME 103 is further responsible to interact with a Home Subscriber Server (HSS) 1 04 for performing user authenticating. The H SS 1 04 is a central database that has stored thereon user-related and subscription- related information.

Further details of the LTE network architecture, its components and the conventional attach procedure may be found in the Technical Specification 3GPP TS 23.401 , Release 1 1 , version 1 1 .1 .0 of the 3rd Generation Partnership Project.

Figure 2 shows a schematic block diagram illustrating relevant MME hardware. The MME 103 comprises a processing unit 208, a memory 209, and a network interface 210. The memory 209 and the network interface 210 are communicatively connected to the processing unit 208. The processing unit 208 may be a microprocessor, Central Processing Unit (CPU), or other suitable processor. The memory 209 may be any suitable volatile or nonvolatile memory or other data storage device. The memory may have computer program code 21 1 stored thereon adapted to cause the processing unit to perform MME-centric processes such as the steps of embodiments of the method described herein that are performed by the MME, e.g. steps described with reference to figures 4 and 5 below. The network interface 210 may comprise any suitable circuitry adapted to provide a network connection to the eNB and other relevant nodes of the LTE network such as the HSS and the SGW. The example of figure 2 shows a processor-implemented embodiment, but alternative embodiments could use hardwired elements or a combination of both.

Figure 3 shows a schematic block diagram of an example of user equipment 101 , such as a mobile telephone, a smart phone, a portable computer, or the like. The wireless communications device 101 comprises a controller 312 and other circuitry and/or hardware components 313 suitably connected to the controller 312. The controller 312 comprises a processing unit 316 and a memory 317 connected to the processing unit. The processing unit 316 may be a microprocessor, Central Processing Unit (CPU), or other suitable processor. The memory 31 7 may be any suitable volatile or non-volatile memory or other data storage device. The memory 317 may have stored thereon data 318 and computer program code 319, the program code 319 being adapted to cause the processing unit 316 to perform processes to be performed by the wireless communications device, such as the steps of embodiments of the method described herein that are performed by the wireless communications device 101 , e.g. steps described with reference to figures 4 and 5 below. The other hardware components/circuitry 313 may comprise a user interface 31 5, e.g. a display, keyboard, keypad, touch screen, and/or the like. The wireless communications device 101 further comprises radio circuitry 314 for radio communication via an antenna 320 with a radio access network, e.g. with the eNB of figure 1 . The example of figure 3 shows a processor-implemented embodiment, but alternative embodiments could use hardwired elements or a combination of both.

Figure 4 schematically illustrates an embodiment of the signalling between the wireless communications device 101 and the MME 103 during the attach procedure for attaching a wireless communications device 101 to the LTE network, e.g. upon power ON of the wireless communications device 101 or when the wireless communications device 101 enters the coverage area of the LTE network. The signalling is performed by means of mobility management and session management messages, also referred to as EPS Mobility Management (EMM) and EPS Session Management (ESM) messages.

The procedure is initiated by the wireless communications device 101 , by sending a PDN connectivity request 421 to the MME 103 via the eNB 102. The request may have the form of an ESM message PDN connectivity request, but modified so as to further include two additional indications:

1 ) an indication of a capability of the wireless communications device to support being EMM attached without EPS bearer/PDN connection, and

2) an indication as to whether the wireless communications device has data to send and wants to make immediate use of the requested PDN connection.

The above indications may be included in the same message. Accordingly, in some embodiments, the connectivity request is a PDN connectivity request comprising at least an indication that the wireless communications device supports being EMM attached without EPS bearer/PDN connection.

Upon receipt of the connectivity request 421 , and if the MME 103 also supports standalone EMM attach without EPS bearer/PDN connection, the MME 103 decodes the additional information from the wireless communications device 101 in step 422. The MME 103 asks for subscription data from the HSS 104, which may include a parameter to indicate an operator preference for the subscription associated with the requesting wireless communications device 101 as to whether standalone EMM attach is preferred or not. If the wireless communications device 101 has indicated that it intends to immediately use the PDN connection, the MME 103 proceeds with the PDN connection establishment as part of the attach procedure as usual. Otherwise it decides whether to establish the PDN connection or not, e.g. depending on the preference received from HSS 104.

It will be appreciated that the HSS parameter may also be a local MME configuration set by the operator, which in that case wi l l be a g lobal preference for all wireless communications devices or potentially separate preference for home subscribers and roaming communication devices or even preferences set per roaming partner. Thus, the MME 103 uses the additional information provided by the wireless communications device, local policy and/or optional subscription information from the HSS 104 to decide whether to accept the PDN connectivity request or to reject it, but where rejecting the PDN connectivity comprises keeping the wireless communications device EMM attached to the wireless

communications network.

If the MME 103 rejects the PDN connectivity request it inserts an appropriate cause value in the response message so as to indicate to the wireless communications device 101 that PDN connectivity was rejected so as to temporarily save resources and, when the wireless communications device 101 has data to send, that the wireless communications device may initiate a new PDN connectivity request.

Responsive to the determination of step 422, the MME 103 thus returns an appropriate message 423 to the wireless communications device 101 via the eNB 102. For exam ple, if the MME 103 decided to establish the PDN connection as part of the EMM attach procedure, it sends an EMM Attach Accept message to the wireless communications device 101 , the message including a piggybacked ESM Activate Default EPS Bearer Context Request according to existing procedures. Otherwise, the MME 103 sends an EMM Attach Accept message containing a PDN Connectivity Reject indicating a predetermined ESM cause code to indicate that the PDN connection was not established, but that the wireless communications device can request it again as standalone procedure at a later point when there is a need for it. Hence, figure 4 illustrates and embodiment of a method for attaching a wireless communications device to a wireless communications network, wherein the wireless communications network comprises at least one control node, and wherein the method comprises:

- receiving by the control node a connectivity request from a wireless communications device, wherein the connectivity request comprises an indication that the wireless communications device supports attachment to the wireless communications network without establishing an association to a packet data network;

In some embodiments, the control node obtains a parameter from a home subscriber server indicative of a policy for accepting a connectivity request by a wireless communications device without establishing an association to a packet data network; the control node may thus base the determination as to whether to provide an attachment of the wireless communications device to the wireless com m unications network with or without establishing an association to a packet data network on the received parameter. The parameter may have a value specific to a subscriber associated with the wireless communications device. In some embodiments, as illustrated in figure 4, the message indicative of the wireless com m unications device being attached to the wireless communications network with establishing an association to a packet data network is an EMM Attach Accept message including an ESM Activate Default EPS Bearer Context Request; and the message indicative of the wireless com m unications device being attached to the wireless communications network without establishing an association to a packet data network may be an EMM Attach Accept message including a PDN Connectivity Reject indicating a predetermined ESM cause code.

Figure 6 illustrates an embodiment of a connectivity request message 421 . The message includes a first data item 630, e.g. a flag, indicating whether the wireless communications device supports attachment to the wireless communications network without establishing an association to a packet data network. The message further includes a second data item 631 , e.g. a flag, indicating whether the wireless communications device has an immediate need for communicating via the data packet network.

Accordingly, in some embodiments of the method disclosed herein, the connectivity request received by the control node further comprises an indication by the wireless communications device whether the wireless communications device has an immediate need for communicating via the data packet network; and wherein determining comprises determ ining to provide an attachment of the wireless communications device to the wireless communications network with or without establishing an association to a packet data network responsive to the received indication.

Figure 7 illustrates an embodiment of a response message 423 from the control node to the wireless communications device. The message includes a fi rst data ite m 732 , e . g . a fl ag , i nd icat i n g whethe r the wi re less communications device is attached to the wireless communications network. The message further includes a cause value 733 indicative of the association to the data packet network being rejected so as to temporarily save resources and of the wireless communications device being able to initiate a new request to establish an association to a data packet network when the wireless communications device has data to send.

It will be appreciated, however, that the indications and/or the cause value may alternatively be inserted in the respective messages in a different way. It will be appreciated that embodiments of an attach procedure may include additional steps, e.g. steps known as such in the art, including additional messages exchanged between the wireless communications device and the MM E and/or between other entities of the com m unications wireless communications network.

In an alternative embodiment the method utilizes a dummy EPS bearer context. In this embodiment, when initiating the EMM Attach procedure (either registering only for EPS services or for both EPS and non-EPS services i.e. a combined EPS/IMSI attach), the wireless communications device includes the piggybacked PDN connectivity request message, but also a further indication that the wireless communications device supports standalone EMM Attach, and additionally an indication of whether the wireless communications device intends to immediately use the requested PDN connection or not.

If the MME also supports standalone EMM attach, the MME decodes the new additional information from the wireless communications device. The MME asks for subscription data from the HSS, which can include a parameter to indicate the operator preference for this subscription of whether standalone EMM attach is preferred or not. If the wireless communications device indicated that it intends to immediately use the PDN connection, the MME proceeds with the PDN connection establishment as part of the attach procedure as usual. Otherwise the MME decides whether to establish the PDN connection or not, e.g. depending on the preference received from HSS. As described above, the HSS parameter can also be a local MME configuration set by the operator, which in that case will be a global preference for all wireless communications devices.

If the MME decided to establish the PDN connection as part of the EMM attach procedure, it sends an EMM Attach Accept message including a piggybacked ESM Activate Default EPS Bearer Context Request according to known procedures. Otherwise it sends an EMM Attach Accept message containing an ESM Activate Default EPS Bearer Context Request but with an additional indication to the wireless communications device that the connection will only be a placeholder/dummy. The placeholder/dummy is not usable by the wireless communications device but merely serves to allow use of existing principles of dependencies between EMM and ESM. The wireless communications device may then initiate a new standalone request procedure again at a later point when there is a need for a PDN connection. Hence, in some embodiments of the method described herein, the message indicative of the wireless communications device being attached to the wireless communications network with establishing an association to a packet data network is an EMM Attach Accept message including an ESM Activate Default EPS Bearer Context Request; and wherein the message indicative of the wireless communications device being attached to the wireless communications network without establishing an association to a packet data network is an EMM Attach Accept containing ESM Activate Default EPS Bearer Context Request comprising an indication to the wireless communications device that the connection is only a placeholder. In yet another embodiment, the process is based on a network broadcast support of the standalone EMM Attach. When the wireless communications network supports the option of standalone EMM Attach (including standalone combined EPS/IMS I attach without any PDN connectivity request), the wireless communications network may ensure that the RAN broadcasts this support, e.g. via a Public Land Mobile Network (PLMN), to support shared networks.

Figure 5 shows a flow diagram of the steps performed by the wireless communications device according to this embodiment of the process. In step 524 t h e wireless communications device reads the broadcast channel/System Information Block (SIB), and determines whether the wireless communications network supports standalone EMM Attach. If the received broadcast information indicates support for standalone attachment ("YES" path out of step 524), the wireless communications device is able to initiate a standalone EMM Attach (i.e. without any PDN connectivity request). Hence, in that case, the wireless communications device may select whether to initiate an EMM Attach with or without PDN Connect Request (step 525); otherwise ("NO" path out of step 524) the wireless communications device uses EMM Attach always with a PDN Request Connect Request (step 526). The M M E receiving the standalone EMM Attach provides required procedures, e.g. as specified in the 3GPP Technical Specification 23.401 (ibid, see e.g. section 5.3.2), except that it does not setup any default bearer. Hence, figure 5 illustrates and embodiment of a method for attaching a wireless communications device to a wireless communications network, wherein the method comprises receiving, by the wireless communications device, a broadcast message from the wireless communications network indicative of whether the wireless com mun ications network supports attachment of a wireless communications device without establishing an association to a packet data network; and wherein the method further comprises sending a connectivity request for requesting attachment to the wireless communications network either with or without establishing an association to a packet data network responsive to the received broadcast message.

Accordingly, in some embodiments the control node causes the wireless communications network to send a broadcast message indicative of whether the wireless communications network supports attachment of a wireless communications device without establishing an association to a packet data network.

In the above, embodiments of a method, a system and apparatus for an efficient attachment of a wireless communications device to a wireless communications network have been described.

Although some embodiments have been described and shown in detail, the aspects disclosed herein are not restricted to them , but may also be embodied in other ways within the scope of the subject matter defined in the following claims. In particular, it is to be understood that other embodiments may be utilized and structural and functional modifications may be made. In particular, embodiments of the aspects disclosed herein have mainly been described with reference to user equipment. It will be understood, however, that embodiments of the methods, devices and systems may also be applied to other types of wireless communications devices, such as MTC devices, or machine-to-machine (M2M) communications devices.

In device claims enumerating several means, several of these means can be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims or described in different em bodiments does not indicate that a com bination of these measures cannot be used to advantage. It should be emphasized that the term "comprises/comprising" when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

Claims

Claims:

1 . A method for attaching a wireless communications device (101 ) to a wireless communications network, the wireless communications network providing data communication, the method comprising communicating, between the wireless communications device and the wireless communications network, an indication (524, 630) that a selected one of the wireless communications device and the wireless communications network supports attachment of the wireless communications device to the wireless communications network without establishing an association to a packet data network (107).

2. A method according to claim 1 , wherein communicating comprises sending a connectivity request (421 ) by the wireless communications device to a control node (103) of the wireless communications network, the connectivity request comprising an indication (630) that the wireless communications device supports attachment to the wireless communications network without establishing an association to a packet data network (107).

3. A method according to claim 1 , wherein the indication is an indication that the wireless communications network supports attachment of a wireless communications device without establishing an association to a packet data network; and wherein communicating the indication comprises receiving (524) a broadcast message by the wireless communications device from the wireless com m unications network indicative of whether the wireless communications network supports attachment of a wireless communications device without establishing an association to a packet data network; and wherein the method further comprises sending a connectivity request (525; 526) responsive to the received broadcast message.

4. A method according to claim 2 or 3, wherein the connectivity request comprises an indication (631 ) by the wireless communications device indicating whether the wireless communications device has an immediate need for communicating via the data packet network.

5. A method for attaching a wireless communications device (101 ) to a wireless communications network, the wireless communications network comprising at least one control node (103), the method comprising:

- communicating an indication (524, 630) that a selected one of the wireless communications device and the wireless communications network supports attachment of the wireless com m un ications device to the wireless communications network without establishing an association to a packet data network;

- determining (422), by the control node, whether to provide an attachment of the wireless communications device to the wireless communications network with or without establishing an association to a packet data network;

- sending a message (423) from the control node to the wireless communications device indicative of whether the wireless communications device is attached to the wireless communications network with or without establishing an association to a packet data network.

6. A method according to claim 5, wherein communicating comprises receiving, by the control node, a connectivity request (421 ) from a wireless communications device; wherein the connectivity request comprises an ind ication (630) that the wireless com m un ications device supports attachment of the wireless communications device to the wireless communications network without establishing an association to a packet data network.

7. A method according to claim 6, wherein the received connectivity request further comprises an indication (631 ) by the wireless communications device whether the wireless communications device has an immediate need for com municating via the data packet network; and wherein determining comprises determining to provide an attachment of the wireless communications device to the wireless communications network with or without establishing an association to a packet data network responsive to the received indication.

8. A method according to claim 5, wherein communicating comprises causing the wireless com m unications network to send a broadcast message indicative of whether the wireless com m unications network supports attachment of a wireless communications device without establishing an association to a packet data network.

9. A method according to any one of claims 5 through 8; wherein determining comprises obtaining a parameter from a home subscriber server (104) indicative of a policy for accepting a connectivity request by a wireless communications device without establishing an association to a packet data network.

10. A method according to claim 9; wherein the parameter has a value specific to a subscriber associated with the wireless communications device.

1 1 . A method according to any one claims 5 through 10, wherein the message indicative of the wireless communications device being attached to the wireless communications network with establishing an association to a packet data network is an EMM Attach Accept message including an ESM Activate Default EPS Bearer Context Request; and wherein the message indicative of the wireless communications device being attached to the wireless communications network without establishing an association to a packet data network is an EMM Attach Accept message including a PDN Connectivity Reject indicating a predetermined ESM cause code.

12. A method according to any one of claims 5 through 1 1 , wherein the message indicative of whether the wireless communications device is attached to the wireless communications network comprises inserting a predetermined cause value (733) into the message, the cause value being indicative of the association to the data packet network being rejected so as to temporarily save resources and of the wireless communications device being able to initiate a new request to establish an association to a data packet network when the wireless communications device has data to send.

13. A method according to any one of claims 5 through 10, wherein the message indicative of the wireless communications device being attached to the wireless communications network with establishing an association to a packet data network is an EMM Attach Accept message including an ESM Activate Default EPS Bearer Context Request; and wherein the message indicative of the wireless communications device being attached to the wireless communications network without establishing an association to a packet data network is an EMM Attach Accept containing ESM Activate Default EPS Bearer Context Request comprising an indication to the wireless communications device that the connection is only a placeholder.

14. A method according to any one of the preceding claims, wherein the wireless communications network is an EPS network.

15. A method according to claim 14, wherein the control node is a Mobility Management Entity.

16. A method according to claim 15 when dependent on claim 2, 6, or 7, wherein the connectivity request is a PDN connectivity request comprising an indication that the wireless communications device supports being EMM attached without EPS bearer/PDN connection.

17. A wireless communications device (101 ) for a wireless communications system, the wireless communications device comprising a processing unit (316) and a radio communications circuit (314); wherein the wireless comm unications device is configured for communication, between the wireless communications device and the wireless communications network, of an indication that a selected one of the wireless communications device and the wireless communications network supports attachment to the wireless communications network without establishing an association to a packet data network.

18. A wireless communications device according to claim 17 wherein the processing unit is configured to cause the radio communications circuit to send a connectivity request (421 ) to a control node (103) of the wireless communications network, wherein the connectivity request comprises an indication (630) that the wireless communications device supports attachment to the wireless communications network without establishing an association to a packet data network.

19. A wireless communications device according to claim 18, further adapted to insert an indication (631 ) into the connectivity request as to whether the wireless communications device has an immediate need for communicating via the data packet network.

20. A wireless communications device according to claim 17, wherein the radio communications circuit is adapted to receive a broadcast message from the wireless communications network indicative of whether the wireless communications network supports attachment of a wireless communications device without establishing an association to a packet data network; and wherein the wireless communications device is further adapted to cause the radio communications circuit to send a connectivity request for requesting attachment to the wireless communications network either with or without establishing an association to a packet data network responsive to the received broadcast message.

21 . A wireless communications device according to any one of claims 17-20, wherein the wireless communications network is an EPS network.

22. A wireless communications device according to claim 21 when

dependent on claim 18 or 19, wherein the connectivity request is a PDN connectivity request comprising an indication that the wireless

communications device supports being EMM attached without EPS

bearer/PDN connection.

23. A control node (103) for a wireless communications network comprising: - an interface circuit (210) adapted to receive a connectivity request (421 ) from a wireless communications device (101 );

- a processing unit (208) adapted to determine (422) whether to provide an attachment of the wireless communications device to the wire less communications network with or without establishing an association to a packet data network; and

wherein the interface circuit is further adapted to send a message (423) to the wireless communications device indicative of whether the wireless communications device is attached to the wireless communications network with or without establishing an association to a packet data network.

24. A control node according to claim 23, wherein the connectivity request comprises an indication (630) that the wireless communications device supports attachment to the wireless communications network without establishing an association to a packet data network (107).

25. A control node according to claim 23 or 24, wherein the received connectivity request comprises an indication (631 ) by the wireless communications device whether the wireless communications device has an immediate need for communicating via the data packet network; and wherein the processing unit is further adapted to cause the control node to provide an attachment of the wireless communications device to the wireless communications network with or without establishing an association to a packet data network responsive to the received indication.

26. A control node according to any one of claims 23 through 25, further adapted to cause the wireless communications network to send a broadcast message indicative of whether the wireless comm unications network supports attachment of a wireless communications device without establishing an association to a packet data network.

27. A control node according to any one of claims 23 through 26; wherein the processing unit is further adapted to obtain a parameter from a home subscriber server (104) indicative of a policy for accepting a connectivity request b y a wireless communications device without establishing an association to a packet data network.

28. A control node according to any one of claims 23 through 27, wherein the message indicative of the wireless communications device being attached to the wireless communications network with establishing an association to a packet data network is an EMM Attach Accept message including an ESM Activate Default EPS Bearer Context Request; and wherein the message indicative of the wireless communications device being attached to the wireless communications network without establishing an association to a packet data network is an EMM Attach Accept message including a PDN Connectivity Reject indicating a predetermined ESM cause code.

29. A control node according to any one of claims 23 through 28, wherein the message indicative of whether the wireless communications device is attached to wireless comprises a predetermined cause value (733), the cause value being indicative of the association to the data packet network being rejected so as to temporarily save resources and of the wireless communications device being able to initiate a new request to establish an association to a data packet network when the wireless communications device has data to send.

30. A control node according to any one of claims 23 through 27, wherein the message indicative of the wireless communications device being attached to the wireless communications network with establishing an association to a packet data network is an EMM Attach Accept message including an ESM Activate Default EPS Bearer Context Request; and wherein the message indicative of the wireless communications device being attached to the wireless communications network without establishing an association to a packet data network is an EMM Attach Accept containing ESM Activate Default EPS Bearer Context Request comprising an indication to the wireless communications device that the connection is only a placeholder.

31 . A control node according to any one of claims 23 through 30, wherein the control node is a Mobility Management Entity.

32. A wireless communications system comprising a wireless

communications device as defined in any one of claims 17-22 and a control node as defined in any one of claims 23 through 31 .